The present invention relates to a new and improved construction of plug-in type program storage.
Modern data processing equipment oftentimes contains different modules or structural elements constructed as storages in which there are fixedly stored certain processing steps, so-called programs.
At the present time there is distinguished between static storages, for instance in the form of relays, capacitors, magnetic cores or complex electronic switching or flip-flop circuits, and dynamic storages in the form of magnetic tapes, magnetic plates or magnetic drums and so forth.
Usually the programs to be stored can be inserted into the storage by means of the same operating elements, such as keyboards, perforated tape readers and the like, as are employed for the insertion of the information to be processed and other commands into the devices.
Oftentimes it is desired that part of the stored information only be accessible to a certain group of people. This is true, for instance, in the case of ciphering devices where the information necessary for enciphering or deciphering respectively, the so-called Basic Key, should only be known to a limited number of people, since the device itself, once it has been programmed, is classified as "secret". For this purpose these devices are equipped for instance with mechanical locks, the keys of which are only possessed by a selective group of people.
Another security measure resides in providing plug-in type modules or units which contain permutable electrical connections which, for instance, can be changed as regards their electric function by soldering- or plug contacts. These do not constitute the actual information storage in the sense that such terminology is presently employed in the data processing art, although their function is similar thereto. As a general rule they cooperate with storages, fixedly mounted at the device, in such a way that the stored data or information can be changed with the aid of such plug-in type or insertable components in terms of their function upon the data processing operation.
Other systems are known in the art where the program carrier is in the form of a perforated or punched card, perforated tape, a magnetic card or the like, which inserts its information into the device through the agency of a reader which is mounted in or connected with the device. In this case there is generally required in the device a second operating storage, since the information stored in the foreign carrier must be transferred via the reader, which is employed as the transducer, into the device and thus is not generally available for use at any moment.